I have no intention of turning you into an air conditioning mechanic. It is a big, hard working, and complicated field. I think it might be nice if you know enough to talk to your repair technician. An educated consumer is a good consumer. The flip side of that coin is that a fool and his money are soon parted.
Of all the ways to cool your home this is the most expensive and complicated. It is also the most effective and some cheaper means cannot be used when there is too much humidity in the air (gulf coast especially). Using this electric refrigeration type of air conditioning with more common sense methods will increase the effectiveness and save your $.
I always thought this process proved that something can be simple and complicated at the same time. Your call.
Of all the ways to cool your home this is the most expensive and complicated. It is also the most effective and some cheaper means cannot be used when there is too much humidity in the air (gulf coast especially). Using this electric refrigeration type of air conditioning with more common sense methods will increase the effectiveness and save your $.
I always thought this process proved that something can be simple and complicated at the same time. Your call.
This picture is of a vehicle air conditioner. It just seemed to be the simplest drawing I could find. It will work so long as you understand that the appearance may be different when you are looking at the equivalent in your home. I will highlight some of those differences at the end of the article.
There are four factoids that have to be true in order for refrigeration to work. They were listed in the previous chapter but here they are again.
Factoid 1 -There is no such thing as cold. Only heat. While true, we will ignore this for the purposes of simplification.
Factoid 2 - The act of evaporation reduces heat. Heat is consumed by the changing of state. For simplicity, just consider it to be magic.
Factoid 3 - Heat will always go to areas of less heat. That is always the flow and it will always try to work. It tries for equilibrium.
Factoid 4 - You make a fluid hotter when you compress it.
I will point out when these processes are being applied.
We will start the process to dump the heat from your home with the expansion valve. Liquid freon (refrigerant) with the heat reduced to the extent possible, will dam up behind the valve once the process starts. Think of it like the faucet on your kitchen sink but in this case you don’t have to manually open it. It is opened and closed by the temperature sensing device the freon must pass through or by on the way out of the coil. It is normally a thermal bulb and a typical expansion valve is pictured below.
When the freon is allowed through the expansion valve (or whatever metering device is used) it expands. Well if compression makes something hotter what will expansion do. It makes it colder (less heat). With the pressure released it also evaporates and what happens to the heat when something evaporates. The heat is released. Good time to reread the factoids above.
In a dry climate an evaporative cooler can be very efficient. It just pulls air through a water pad and cools it. The dry climate is key because it would be miserable on the gulf coast and probably effective on the dry west coast.
Back to the drawing. This cold refrigerant has warm air from your house pass over it. It sucks that heat from the air (factoid 3) through the copper or aluminum pipe making the air colder (less heat). That also makes it drop below the dew point normally and the air gives up it’s humidity. That water is drained to the sewer via plastic (normally) pipes or out the bottom of your car.
The freon then contains considerable heat from the house and it needs to dump it. Even with this heat it is normally cooler than the temperature of the outside air and cannot give up it’s heat to a medium that is cooler than itself. What next? Compress it. Factoid 4.
The pipe that comes off your compressor is hot enough to leave scars. Ask me how I know. You can feel it being dumped by feeling the air exhaust from the outside unit. It normally escapes from the top of the unit pictured below. It is pushed through the coil and we are back where we started. This metering device is normally located at the evaporator coil. This freon is cooled by the outside air and condenses (turns to liquid). If you are charged correctly there is liquid freon from the coil all the way up to the evaporator coil. It is a dam and you just completed the refrigerant cycle.
There are four factoids that have to be true in order for refrigeration to work. They were listed in the previous chapter but here they are again.
Factoid 1 -There is no such thing as cold. Only heat. While true, we will ignore this for the purposes of simplification.
Factoid 2 - The act of evaporation reduces heat. Heat is consumed by the changing of state. For simplicity, just consider it to be magic.
Factoid 3 - Heat will always go to areas of less heat. That is always the flow and it will always try to work. It tries for equilibrium.
Factoid 4 - You make a fluid hotter when you compress it.
I will point out when these processes are being applied.
We will start the process to dump the heat from your home with the expansion valve. Liquid freon (refrigerant) with the heat reduced to the extent possible, will dam up behind the valve once the process starts. Think of it like the faucet on your kitchen sink but in this case you don’t have to manually open it. It is opened and closed by the temperature sensing device the freon must pass through or by on the way out of the coil. It is normally a thermal bulb and a typical expansion valve is pictured below.
When the freon is allowed through the expansion valve (or whatever metering device is used) it expands. Well if compression makes something hotter what will expansion do. It makes it colder (less heat). With the pressure released it also evaporates and what happens to the heat when something evaporates. The heat is released. Good time to reread the factoids above.
In a dry climate an evaporative cooler can be very efficient. It just pulls air through a water pad and cools it. The dry climate is key because it would be miserable on the gulf coast and probably effective on the dry west coast.
Back to the drawing. This cold refrigerant has warm air from your house pass over it. It sucks that heat from the air (factoid 3) through the copper or aluminum pipe making the air colder (less heat). That also makes it drop below the dew point normally and the air gives up it’s humidity. That water is drained to the sewer via plastic (normally) pipes or out the bottom of your car.
The freon then contains considerable heat from the house and it needs to dump it. Even with this heat it is normally cooler than the temperature of the outside air and cannot give up it’s heat to a medium that is cooler than itself. What next? Compress it. Factoid 4.
The pipe that comes off your compressor is hot enough to leave scars. Ask me how I know. You can feel it being dumped by feeling the air exhaust from the outside unit. It normally escapes from the top of the unit pictured below. It is pushed through the coil and we are back where we started. This metering device is normally located at the evaporator coil. This freon is cooled by the outside air and condenses (turns to liquid). If you are charged correctly there is liquid freon from the coil all the way up to the evaporator coil. It is a dam and you just completed the refrigerant cycle.
It is now ready to escape, decompress, evaporate, and cool and dehumidify the air in the home all over again. There may or may not be filters or dryers attached. If they are they can normally be found in the copper pipes by the outside unit.
Sometimes just seeing things drawn in a different way can make things become more clear. This picture is missing the fans and it is drawn in a slightly different format which might make it easier to understand. If it helps, drag the picture to your desktop and read the paragraphs above while looking at this. When you are done with the article see how many components you can identify in your own home. They will probably look more like some of the pictures that follow.
Sometimes just seeing things drawn in a different way can make things become more clear. This picture is missing the fans and it is drawn in a slightly different format which might make it easier to understand. If it helps, drag the picture to your desktop and read the paragraphs above while looking at this. When you are done with the article see how many components you can identify in your own home. They will probably look more like some of the pictures that follow.
Although not as precise as a thermal expansion valve this is much more common and except for the occasional clogged cap tube it is less troublesome.
The liquid freon is allowed to dam up against the small cap tube and when it bursts through it expands, evaporates, and gets cold just like an expansion valve system. There is no opening and closing of this unit. It is just dammed up by pressing against a small opening (the opening(s) is/are the cap tube(s) themselves). The pressures will always equalize when shut down which reduces starting pressures and wear on your compressor.
In this picture, the freon goes in the smaller of the two copper tubes (bottom tube) and bursts through the four capillary tubes to different places in the coil. When it has expanded and evaporated it returns through the four medium sized tubes at the top into the very large copper tube. Then it returns to the condenser.
Another type metering device is the flowrater system which has different sized fixed openings that perform the same function. It looks like this but minus the cap tubes.
The liquid freon is allowed to dam up against the small cap tube and when it bursts through it expands, evaporates, and gets cold just like an expansion valve system. There is no opening and closing of this unit. It is just dammed up by pressing against a small opening (the opening(s) is/are the cap tube(s) themselves). The pressures will always equalize when shut down which reduces starting pressures and wear on your compressor.
In this picture, the freon goes in the smaller of the two copper tubes (bottom tube) and bursts through the four capillary tubes to different places in the coil. When it has expanded and evaporated it returns through the four medium sized tubes at the top into the very large copper tube. Then it returns to the condenser.
Another type metering device is the flowrater system which has different sized fixed openings that perform the same function. It looks like this but minus the cap tubes.
This is what a thermal expansion valve actually looks like. This bulb (lower left corner) and capillary tube contains a refrigerant that expands and contracts. When the freon is hot and expanded it opens the valve. When it cools down and contracts it closes that valve.
It is a lot more complicated than it sounds as the bulb must be insulated and situated exactly on the pipe. If someone charges your unit with refrigerant without checking the type of metering device you should ask how and why. An AC check should always include looking at the evaporator area. It's quick to do and you really cannot properly charge a unit if you don't know about the metering device.
It is a lot more complicated than it sounds as the bulb must be insulated and situated exactly on the pipe. If someone charges your unit with refrigerant without checking the type of metering device you should ask how and why. An AC check should always include looking at the evaporator area. It's quick to do and you really cannot properly charge a unit if you don't know about the metering device.
This is the housing for the compressor and the outside coil. Since it is the place that the freon is condensed and cooled it is called a condensing unit. It has a coil guard by design. Many do not but they protect it from weedeaters and/or lawnmower debris. It makes it a little harder to clean but overall probably is beneficial.
About a minute into the cooling process the refrigerant may become so hot you cannot hardly hold your hand in the airflow coming out the top of the unit. As your home becomes cooler that heat decreases.
My intention is to go into each part of this and what can go wrong in future chapters. There is actually quite a lot that can go wrong but you are less gullible when you understand what they do when things are going right.
About a minute into the cooling process the refrigerant may become so hot you cannot hardly hold your hand in the airflow coming out the top of the unit. As your home becomes cooler that heat decreases.
My intention is to go into each part of this and what can go wrong in future chapters. There is actually quite a lot that can go wrong but you are less gullible when you understand what they do when things are going right.
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